First, the facts. What we have here is the President of the United States openly threatening the recently-deposed FBI director to stay silent. At issue, primarily, is the claim made by Trump that Comey told him, on three separate occasions, that he was not under investigation. That would represent a major breach of protocol on Comey's part and would raise serious questions about conflicts of interest -- the same sort of questions that led then Attorney General Loretta Lynch to recuse herself from the Clinton email investigation after former President Bill Clinton boarded a plane to talk to her.

Comey has yet to speak publicly about Trump's claims but his allies, without their names attached, have described the idea that he would have told the President that he wasn't under investigation as "literally farcical," according to a report in the Wall Street Journal.

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Trump seems very interested in keeping Comey silent. Which raises all sorts of questions. Does Trump know Comey knows things that would undercut his assertions about either their conversations, the ongoing Russia investigation or something else? Does Trump really believe the best way to keep Comey quiet is to publicly threaten him? If so, why?

Then there is the fact that Trump insinuates that he did -- or could -- tape conversations with Comey, giving him a way to prove, theoretically, that he is telling the truth (and Comey isn't) about their conversations.

The last president who taped his conversations was a guy named Richard Milhous Nixon. (Regular taping of phone calls made by the president has been largely verboten since then; read this amazing piece by Yahoo's Olivier Knox on that.) It didn't end all that well for Nixon if you remember.

That Trump would invoke the specter of Nixon at the end of this week is truly startling. His dismissal of Comey led to a slew of comparisons to Nixon's firing of special prosecutor Archibald Cox, who had been appointed by Congress to look into the Watergate break-in. Less than 24 hours later, Trump did a surprise photo-op with Henry Kissinger, who served as Nixon's Secretary of State.

It's not clear from the wording of Trump's tweet whether he actually was taping conversations with Comey or simply using the idea of doing so as a sort of Sword of Damocles to hang over the head of the former FBI director. Either way, it's very strange, to say the least.

While all of Trump's presidency -- the entire 112 days of it -- has had a lurching, zig-zag feel to it, the last 72 hours -- and, especially, the last 24 -- feel even more erratic and unpredictable. Where can Trump possibly go from here?